Preparation Of Modified Epoxy Coating Based On Molybdenum Disulfide And Its Corrosion Resistance

Metal corrosion not only causes huge economic losses,but also wastes resources.Severe metal corrosion can also cause structural failures that can lead to personal injury or death.Therefore,it is of great significance to strengthen the research on corrosion and protection of metals.The organic coating protection method is a relatively simple,economical and effective method for preventing metal corrosion.Epoxy resin coatings have a wide range of applications in the field of anti-corrosion due to their high strength,low shrinkage,excellent adhesion and good chemical resistance.In order to further improve the anticorrosive effect of epoxy coatings,two-dimensional nanomaterials such as graphene（GO）,boron nitride（BN）,molybdenum disulfide（MoS₂）,etc.are usually added to the epoxy resin to improve the various performances of epoxy coating.However,the untreated two-dimensional nanomaterials tend to agglomerate in the epoxy resin,which in turn reduces the corrosion resistance of the epoxy coating.Based on the optimization of the epoxy anti-corrosion coating formulation,the two-dimensional nanomaterial molybdenum disulfide was modified with polydopamine and fluorine-containing silane and the modified product was added to the epoxy resin to improve the corrosion resistance.The specific research contents of this paper are as follows:（1）The epoxy curing agent was screened.By comparing the physical properties,salt-resistant properties and the EIS test of epoxy resin E44 with different curing agents（J-650,NX2016,NC562,NX541X90）,it is concluded that the corrosion resistance of cashew phenolic curing agents（NX2016,NC562,NX541X90）is better than that of polyamide curing agents（J-650）.（2）Polydopamine modified molybdenum disulfide（MoS₂@PDA）and its properties in epoxy anticorrosive coatings.MoS₂@PDA was prepared by oxidative self-polymerization of dopamine in Tris buffer solution,and catechol and amino functional groups were introduced on the surface of MoS₂.The effect of the addition of MoS₂@PDA on the anticorrosion performance of epoxy resin was investigated.Tests by various characterizations showed that the PDA was successfully grafted onto the surface of MoS₂.The results show that grafting PDA on the surface of molybdenum disulfide can greatly improve the dispersibility of molybdenum disulfide in epoxy coating,thus improving the anticorrosive performance of epoxy composite coating.Compared with pure epoxy（EP）coating,the adhesion of MoS₂@PDA/EP coating increased nearby 3 Mpa,and the corrosion resistance of MoS₂@PDA/EP coating increased nearby three orders of magnitude.It can be seen from the polarization curve that the corrosion potential and corrosion current density of the MoS₂@PDA/EP coating are smaller than the corrosion potential and corrosion current density of the MoS₂/EP coating and the EP coating.The above adhesion and electrochemical analysis show that the addition of MoS₂@PDA can significantly improve the corrosion resistance of epoxy coatings.（3）Polydopamine,fluorine-containing silane modified molybdenum disulfide（MoS₂-F@PDA）and its properties in epoxy anti-corrosion coatings.MoS₂-F was prepared by grafting 1H,1H,2H,2H-perfluorooctyltrichlorosilane on the surface of MoS₂,and then grafting PDA to prepare MoS₂-F@PDA.The effect of the addition of MoS₂-F@PDA on the anticorrosive properties of epoxy resin was investigated.The results show that compared with MoS₂@PDA/EP,the corrosion resistance of MoS₂-F@PDA/EP is one order of magnitude larger than that of MoS₂@PDA.It can be seen from the polarization curve that the corrosion potential and corrosion current of the MoS₂-F@PDA/EP coating are smaller than the corrosion potential and corrosion current of the MoS₂@PDA/EP coating.The equivalent circuit diagram fitting by Zsimpwin software found that the MoS₂-F@PDA/EP coating was still in the early stage of corrosion after immersion for 312 h,while the MoS₂@PDA/EP coating was already in the middle of corrosion.